National Harbor: The Air Force has cleared the nation’s highest performance fighter, the F-22, for return to flight but the service, unable to pinpoint the reasons for at least one worrying incident of what clearly appeared to be hypoxia, has decided to increase medical monitoring of pilots.

“We now have enough insight from recent studies and investigations that a return to flight is prudent and appropriate,” Air Force Chief of Staff Norton Schwartz said in a statement. “We’re managing the risks with our aircrews, and we’re continuing to study the F-22′s oxygen systems and collect data to improve its performance.”

A key part of managing that risk will be very close monitoring of pilots’ physiology. The service plans to build a medical baseline for all F-22 pilots. When they land, they will be tested if they show any adverse medical signs.

In a question and answer session with reporters today, Schwartz said the Air Force will slowly ramp up flight duties for the F-22 pilots. Each aircraft will be inspected. each pilot will be equipped with “certain protective equipment and data gathering equipment,” he said. Each pilot will be trained and brought back up to speed on emergency procedures. I understand that one of the F-22 pilots who suffered from hypoxia apparently ignored warnings from the airplane that his oxygen flow had been cut off as a safety measure. Since the plane performed as expected, that incident did not shape the Safety Investigation Board’s conclusions about the oxygen system. But it apparently has shaped the board’s recommendations to ensure pilots do not do the same thing again.

Schwartz said the Air Force will also gather more data from the airplane “to build our confidence that we know what is transpiring in the airplane.” And that gets to the nub of what happened with the F-22. The service simply isn’t sure what went wrong, but is confident that there were few enough incidents that the aircraft is fundamentally safe. “We do not have a smoking gun here. That is the bottom line,” he said. But, as Schwartz told us, they gathered the “best minds” to review the aircraft’s systems, the safety reports and the 16 test flights flown to gather more data after the F-22 fleet was grounded.